JP2012527767A - Electrical insulated heat dissipation junction box - Google Patents

Abstract

A junction box used to make an electrical connection to a photovoltaic panel. The junction box has two chambers including a first chamber and a second chamber, and a shared wall separating both chambers. The walls may be configured to have an electrical connection therebetween. These two lids are each configured to seal two chambers. The two lids are on the opposite side of the junction box with respect to the photovoltaic panel. The two lids may be attachable using different sealing processes to have different sealing degrees. The first chamber may be configured to receive a circuit board. The junction box may include a support for attaching the printed circuit board to the first chamber. The second chamber is configured for electrical connection to the photovoltaic panel. The metal heat sink may be bonded in the first chamber. The first chamber is configured to receive a circuit board for power conversion, and the metal heat sink is configured to dissipate heat generated by the circuit board.

Description

  The present invention relates to a connection box for a power source, and more particularly to a connection box electrically connected to a photovoltaic panel.

  A photovoltaic module or photovoltaic panel is a packaged, interconnected assembly of photovoltaic cells, also called solar cells. Since a single photovoltaic module can only produce a limited amount of power, commercial installations include multiple modules or panels interconnected in series and parallel in the form of a solar cell array. Electrical connections are made in series to achieve the desired output power and / or to provide the desired amount of current source capability. Solar cell installations generally include photovoltaic modules, inverters, batteries, and interconnect wires.

  When a portion of the photovoltaic module is shaded, the shaded battery does not produce the same current as the unshaded battery. Since solar cells are connected in series, the same amount of current must flow through all the cells connected in series. A battery that is not shaded forces more current through the shaded battery. The only way to allow the shadowed battery to operate at higher currents is to operate in the negative voltage region causing a net voltage loss in the system. The value obtained by multiplying the current by this negative voltage is the negative power generated by the battery that is shaded. The shadowed battery dissipates power as heat, creating a “hot spot”. The bypass diode is thus integrated with the photovoltaic module so that the battery does not overheat if the photovoltaic module is partially shaded.

  Blocking diodes block reverse current from the battery to the module at night and reverse current from modules connected in parallel to damaged modules during the day. May be placed in series with the battery or module to block leakage.

  The electrical module is a photovoltaic that performs electrical conversion such as direct current (DC) to direct current conversion, electrical inversion such as a microinverter, or other functions such as performance monitoring and / or anti-theft. It may be integrated with the module.

  U.S. Pat. No. 7,729,036 discloses a solar cell connection system that includes a junction box that uses surface mounted diodes attached to a printed circuit board inside the junction box. The junction box optionally includes a metal plate attached within the lid of the junction box as a heat sink for dissipating heat from the diode.

As used herein, the term “cable gland” refers to a device used at the entrance of an electrical cable or cord that is inserted into an electronic device and securely secures the electrical cable inserted into one of the electronic devices. Used for.
The term “in-situ” in the context of the present invention refers to being bonded or attached in the manufacturing process, rather than being attached after the manufacture of the part, for example injection molding.

  In accordance with the present invention, a junction box is provided that is used to make an electrical connection to a photovoltaic panel. The junction box has two chambers, including a first chamber and a second chamber, and a shared wall separating both chambers. The walls may be configured to have an electrical connection therebetween. These two lids are each configured to seal two chambers. The two lids are configured on the opposite side of the junction box with respect to the photovoltaic panel. The two lids may be attachable using different sealing processes. One lid may be configured to seal the first chamber, and the other lid may be configured to seal the second chamber with a seal degree different from the seal degree of the first chamber. The first chamber may be configured to receive a circuit board for power conversion of the power output of the photovoltaic panel. The junction box may include a support for attaching the printed circuit board to the first chamber. The second chamber is configured for electrical connection to the photovoltaic panel. The second chamber may optionally be configured to include a diode, such as a bypass and / or blocking diode. The junction box may have electrical connection terminals attached inside the second chamber for connection of the circuit to the photovoltaic panel. The metal heat sink may be bonded in the first chamber. The first chamber is configured to receive a circuit board for power conversion, and the metal heat sink is configured to dissipate heat generated by the circuit board. The heat sink is arranged by injection molding in the manufacturing process of the junction box. The junction box may further include a pad configured for heat conduction and electrical insulation between the circuit board and the metal heat sink. The metal heat sink may include a dovetail structure that is configured to prevent the junction box and the metal heat sink from separating from each other. The dovetail structure may be a cavity.

  The present invention provides a junction box used for making electrical connections to photovoltaic panels. The junction box has a metal heat sink that is bonded in situ to the first chamber. The first chamber is configured to receive a circuit board for power conversion, and the metal heat sink is configured to dissipate heat generated by the circuit board. The junction box may optionally have two chambers, including a first chamber and a second chamber, and a shared wall separating both chambers. The two lids are each configured to seal the two chambers. The metal heat sink may include a dovetail structure that is configured to prevent the junction box and the metal heat sink from separating from each other. 19. This wall may have an electrical connection through it.

  The present invention is described herein by way of example only and with reference to the accompanying drawings.

FIG. 1A is an isometric view of a junction box according to one embodiment of the present invention. FIG. 1B is an isometric view of a junction box according to one embodiment of the present invention. It is the detail of the cross section XX of the junction box shown with the broken line of FIG. 1A. It is the detail of the cross section YY of the junction box shown with the broken line of FIG. 1A. FIG. 3A is an isometric view of a heat sink according to another embodiment of the present invention. FIG. 3B is an isometric view of a heat sink according to another embodiment of the present invention.

  The foregoing and / or other aspects will become apparent when considered in conjunction with the accompanying drawings and the following detailed description.

  Reference will now be made in detail to embodiments of the invention, examples of which are illustrated in the accompanying drawings. Like reference numerals refer to like elements throughout. Embodiments are described hereinafter to describe the present invention by referring to these drawings.

  Through the introduction, the diode and / or the electrical module in the junction box attached to the photovoltaic module dissipate heat. When using an insulated junction box, most of the heat must be dissipated from the air inside the junction box. If a metal junction box is used, heat may be dissipated directly from the junction box. However, the use of a metal junction box can be inconvenient due to metal surfaces that can be grounded and regulations that require additional wiring to be provided.

  Before the embodiments of the present invention are described in detail, the present invention is not limited to application to the details of the component design described in the following description or illustrated in the drawings. The invention can be practiced or carried out in other embodiments or in various ways. It will also be appreciated that the terminology and terminology used herein is for the purpose of description and should not be considered limiting.

  Referring now to the drawings, FIG. 1A is an isometric view 10A of a junction box 12 according to an embodiment of the present invention. The junction box 12 is shown attached to the back surface (or non-photovoltaic side) 4 of the photovoltaic panel 16. The connection box 12 has a cable gland 130 that can terminate the cable inside the connection box 12. The junction box 12 has an outer casing 102 and uses the lid 106 to access the junction box 12.

  FIG. 1B is an isometric view of the underside of the junction box 12 removed from the photovoltaic panel 16. This isometric view shows the ground 130 and the two parts A and B of the junction box 12. Chamber A is partitioned by dimension Z × X, and chamber A is covered by a lid 108. The chamber 108 of the junction box 12 can be accessed from the lid 108. Chamber B is an open section partitioned by dimension X × Y, and terminal 104 appears. The bypass diode 110 is connected between the terminals 104. In accordance with a feature of the present invention, the lid 106 removed to access chamber B and the lid 108 used to access chamber A are on the opposite side of junction box 12.

  FIG. 2A is a diagram showing details of a cross section XX of the junction box 12 shown by a broken line in FIG. 1A and shows the feature of the present invention. Section XX shows chamber portions A and B of junction box 12 attached with clip 216 to non-photovoltaic side 4 of photovoltaic panel 16. A mechanical fastener using a clip 216 between the junction box 12 and the photovoltaic panel 16 allows the junction box 12 to lie flat on the photovoltaic panel 16 and uses a gasket to chamber B. The open end may be sealed.

  Chamber A includes a circuit board 260, a heat conductive pad 262, a heat sink 264, the outer casing 102, and the lid 108. The circuit board 260 is preferably mounted on a support adapted to receive the circuit board 260. The thermal pad 262 provides electrical insulation and thermal conductivity between the heat sink 264 and the circuit board 260. The component side of the circuit board 260 is preferably in contact with the thermal pad 262 such that heat generated by the component of the circuit board 260 is dissipated by the heat sink 264 through the thermal pad 262. Radio frequency interference (RFI) discharged from the junction box 12 as a result of the operation of the circuit board 260 is reduced by covering the sides of the lid 108 with an electrically conductive shield 108a. The shield 108 a is electrically connected to the heat sink 264 to form a Faraday box that suppresses RFI discharge from the connection box 12.

  The lid 108 according to aspects of the present invention is preferably manufactured in an injection molding process. The shield 108a may be disposed in the original position during the injection molding process of the lid 207 and adhered to the lid 108 during the injection molding process. Thus, when the lid 108 is attached to the chamber A of the box, the connection box 12 is electrically insulated by the heat sink 264 and the shield 108a. The outer housing 102 and lid 108 further provide non-electrical conductor insulation for the heat sink 264 and shield 108a between the back surface 4 of the panel 16 and the outside of the junction box 12. The lid 108 is optionally sealed to the chamber A permanently and / or tightly.

  Chamber B includes terminal 104, support 214, bypass diode 110, lid 106, bus bar 212, and wall 202. Wall 202 provides physical separation between chamber portions A and B. The electrical connection between the circuit board 260 in the chamber A and the electrical connector 104 in the chamber B is via the bus bar 212. The bus bar 212 is hermetically sealed in the wall 202 in such a way as to maintain the intended hermeticity of the chamber A, for example to prevent ingress of water or humidity. The electrical connector 104 and the bus bar 212 are mechanically supported by a support portion 214. The support 214 also provides a hermetic seal and / or electrical insulation between one end of the connector 104 that connects to the bus bar 212 and the other end of the connector 104 that connects to the connection provided by the photovoltaic panel 16. You can do it. The bypass diode 110 connected to the connector 104 may be disposed between the support portion 214 and the back surface 4 of the panel 16 or between the support portion 214 and the lid 106. Lid 106 provides access to chamber B, while junction box 12 is physically attached to photovoltaic panel 16 but is electrically isolated from panel 16. The preferred mechanism for attaching the lid 106 to the junction box 12 is hermetically sealed using an array of rubber gaskets to protect chamber B from being sealed, for example, from water / humidity entering the chamber B from the lid 106. That is.

  According to another embodiment of the present invention, the junction box 12 is constructed with a double wall 202 in which chamber A and chamber B are separable and reattachable. Similarly, the connector 212 can be reconnected between chamber A and chamber B. In this embodiment, a failure of the circuit board 260 in the electronics can be repaired by replacing chamber A with a new circuit board 260 and chamber B without being removed from the photovoltaic panel 16. Similarly, upgrading electronic equipment is easy.

  Junction box 12, including housing 102, lid 108/106, heat sink 264, thermal pad 262, is applicable for connection to IEC 61215 (Ed.2) temperature and insulation standards or other photovoltaic panels. It is preferred that it conforms to industry standards. Junction box 12 and lid 108/106 are made of a thermosetting resin such as acrylonitrile butadiene styrene (ABS), thermoplastic, polybutylene terephthalate resin (PBT), poly (p-phenylene oxide) (PPO), or epoxy resin. It may be manufactured by injection molding.

  FIG. 2B is a diagram illustrating details of a cross-section YY of the junction box 12 indicated by a broken line in FIG. The cross section YY is a cross section of the chamber A attached to the back surface 4 of the photovoltaic panel 16. Cross section YY shows the outer housing 102, the heat sink 264 having a dovetail structure 264, a heat conductive pad 262, a circuit board 260 and a lid 108 having an electrical shield 108a.

  The manufacture of the box chamber portions A and B of the junction box 12 in the preferred embodiment of the present invention is by an injection molding process. The heat sink 264 with or without the dovetail 264a during the injection molding process is placed inside the chamber A and bonded in situ to the box chamber A as a result of the injection molding process.

  In order to further increase the adhesion strength between the heat sink 264 and the box chamber A, the heat sink 264 may be provided in an integrated part, and may be provided by a joint structure 264a. Due to the further function of the dovetail 264a, the adhesion between the heat sink 264 and the chamber A is such that the connection box 12 is attached to the electronic components operating inside the chamber A, the ambient heat level, and the photovoltaic panel attached Guarantees that the box 12 will not be damaged when exposed to thermal stress as a result of exposure to sunlight. Here, fasteners such as screws are used to secure the chamber A to the heat sink 202, and the horizontal dimension of the dovetail structure 264a generally expands to accommodate the size of the fasteners. A further feature of the dovetail structure 264a is a cavity structure within the dovetail 264a that allows deformation of the dovetail 264a. The deformation of the dovetail 264a allows the housing 102 and the heat sink 264 / dovetail 264a to take various degrees of thermal expansion when the adhesion between the heat sink 264 and the casing 102 of the chamber A is cured / cooled.

  Reference is now made to FIGS. 3A and 3B showing isometric views of a heat sink 264 in accordance with another embodiment of the present invention. The heat sink 264 has four holes 302. The hole 302 is used to attach the heat sink 264 to the chamber A of the connection box 12 using screws. The attachment of the heat sink to the chamber A may be performed as an additional procedure after the injection molding of the connection box 12 or as an additional procedure of the connection box 12 which is not injection molded. An additional thermal pad may be placed between the heat sink 264 and the housing 102 to ensure good contact between the heat sink 264 and the housing 102 after the heat sink 264 is attached to the housing 102. The deformable nature of the thermal pad is used to accommodate the non-uniform surfaces of the heat sink 264 and housing 102 that result from the manufacture of the heat sink 264 / housing 102. Alternatively, a heat conductive adhesive or an embedded material may be disposed between the heat sink 264 and the housing 102.

  As used herein, the articles “a” and “an” mean “one or more”. For example, “a heat-sink” and “a circuit board” have the meaning of “one or more heat (s)” and “one or more heat-sinks” Multiple heat sinks) "or" one or more circuit boards ".

  While selected embodiments of the present invention have been shown and described, it will be understood that the present invention is not limited to only the described embodiments. On the contrary, modifications to these embodiments may be recognized without departing from the principles, spirit, scope of the claims, and other equivalent content.

Claims (20)

A junction box used to make electrical connections to photovoltaic panels,
Two chambers including a first chamber and a second chamber;
With a shared wall separating both chambers,
Two lids configured to seal each of the two chambers;
Junction box with.   The junction box according to claim 1, wherein the two lids are configured on the opposite side of the junction box with respect to the photovoltaic panel.   The junction box of claim 1, wherein the wall is configured to have an electrical connection therethrough.   The junction box of claim 1, wherein the two lids are attachable using different sealing processes.   One of the two lids configured to seal the first chamber and the other of the two lids sealing the second chamber with different degrees of sealing. The junction box according to claim 1.   The junction box according to claim 1, wherein the first chamber is configured to receive a circuit board for power conversion of power output of the photovoltaic panel.   The junction box according to claim 1, further comprising a support for attaching a printed circuit board to the first chamber.   The junction box of claim 1, wherein the second chamber is configured for electrical connection to the photovoltaic panel.   The junction box of claim 1, wherein the second chamber is configured to include a diode.   The junction box according to claim 1, further comprising an electrical connection terminal for connecting a circuit to the photovoltaic panel, wherein the electrical connection terminal is mounted in the second chamber.   The junction box according to claim 1, further comprising a metal heat sink adhered in the first chamber.   12. The connection of claim 11, wherein the first chamber is configured to receive a circuit board for power conversion, and the metal heat sink is configured to dissipate heat generated by the circuit board. box.   12. The junction box according to claim 11, wherein the heat sink is cast in-situ during an injection molding process of manufacturing the junction box.   The junction box of claim 11, wherein the metal heat sink includes a dovetail structure configured to prevent mutual separation of the metal heat sink and the junction box.   15. A junction box according to claim 14, wherein the dovetail structure is a cavity.   The junction box according to claim 11, further comprising a pad configured to conduct heat and electrically insulate between the circuit board and the metal heat sink.   An electrically isolated junction box used to make an electrical connection to a photovoltaic panel, wherein the heat sink is a metal heat sink bonded in-situ within the first chamber. One chamber receives a circuit board for power conversion, and the metal heat sink includes a heat sink configured to dissipate heat generated by the circuit board. The electrically insulated junction box according to claim 17, further comprising:
Two chambers including a first chamber and a second chamber;
With a shared wall separating both chambers,
Two lids configured to seal each of the two chambers;
Junction box with.   The electrically insulated junction box of claim 17, wherein the metal heat sink includes a dovetail structure configured to prevent mutual separation between the heat sink and the junction box.   The electrically insulated junction box of claim 17, wherein the wall is configured to have an electrical connection therethrough.

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